268 



BACTERIOLOGICAL CHEMISTRY 



CH 



CH 



C.CONH2 



II I 



CH (m 



\ // 



:C.NH2 



I 



CH C— No 



^CH 



/. 



N- 



-C— N- 



I 

 CH- 



I 

 HOC.H 



■ I 

 HOC.H 



I 

 HC - 



I 

 (JH., 



I OH 



I 

 — P — 



II 



o 



0- 



CH— 

 HOC.H 



HOC.H 



I 

 HC 



P _ _ CH, 



in which nicotinamide and adenine are joined by two 

 molecules of ribose-5-phosphate. Its function is to act 

 as a hydrogen carrier between phosphoglyceraldehyde 

 and acetaldehyde, being reduced to dihydro -co -enzyme I 

 by the former and re-oxidised by the specific flavo- 

 protein enzyme with acetaldehyde as the hydrogen 

 acceptor (see pp. 203 and 276). Co-enzyme I is very 

 widely distributed and participates in the respiration of 

 many bacteria, particularly those producing lactic acid 

 by fermentation. It is to be found in nearly all animal 

 tissues, in red blood corpuscles, plants, fungi and bacteria. 

 It is a growth factor for some members of the genus 

 Hcemo'philus. 



The closely related co -enzyme II, triphosphopyridine 

 nucleotide containing an extra phosphate group, plays 

 the same role of hydrogen carrier in animal tissues in 

 the conversion of glucose to lactic acid. 



In view of the discovery of the necessity of magnesium 

 salts as well as the co -enzyme in yeast fermentation the 

 following terminology for the enzyme systems concerned 

 has been proposed : Zymase to indicate the pure enzyme 



